28uc | pdb_000028uc
LASV cap-snatching endonuclease in complex with BXA - serial synchrotron crystallography
Structural highlights
FunctionQ6GWS2_LASSJ RNA-dependent RNA polymerase, which is responsible for the replication and transcription of the viral RNA genome using antigenomic RNA as an intermediate. During transcription, synthesizes subgenomic RNAs and assures their capping by a cap-snatching mechanism, which involves the endonuclease activity cleaving the host capped pre-mRNAs. These short capped RNAs are then used as primers for viral transcription. The 3'-end of subgenomic mRNAs molecules are heterogeneous and not polyadenylated. The replicase function is to direct synthesis of antigenomic and genomic RNA which are encapsidated and non capped. As a consequence of the use of the same enzyme for both transcription and replication, these mechanisms need to be well coordinated. These processes may be regulated by proteins N and Z in a dose-dependent manner.[HAMAP-Rule:MF_04086][PIRNR:PIRNR000836] Publication Abstract from PubMedEmerging human pathogenic RNA viruses such as Lassa virus (LASV) and closely related viruses such as Hantavirus and Andes virus continue to be a major health threat globally. Treatment options for infections are severely limited. The widely conserved cap-snatching endonuclease of LASV (LASVendoN) is therefore used as an interesting drug target for our X-ray compound-screening experiments. Considering recent improvements in instrumentation and serial crystallography method development, different approaches may be used to facilitate pharmaceutical compound screening. Current-generation X-ray free-electron laser (XFEL) sources hold promise for obtaining higher quality diffraction data and achieving a high sample throughput using fixed-target serial femtosecond X-ray crystallography. We collected serial fixed-target X-ray diffraction data at Linac Coherent Light Source and at the synchrotron source PETRA III for comparison and solved the crystal structures of 2,4-dioxo-4-phenylbutanoic acid (DPBA) and baloxavir acid (BXA) binding to the active site of LASVendoN. These solved structures represent a reasonable starting point for drug development. In addition to room-temperature diffraction data, conventional single-crystal diffraction data were recorded at 100 K for comparison. To analyse the sample throughput in a compound-screening experiment at an XFEL, we further present data for the bacterial fosfomycin-resistance protein A with six ligands previously identified in a synchrotron screening experiment. In summary, the XFEL and synchrotron data-collection approaches have proven to be useful for compound screening with minor differences in achievable data quality and resolution. The individual experimental setup, detector and potentially the use of beam sweeping at XFELs at close-to-physiological temperatures combined with reasonable sample consumption and minimized radiation damage are considered to be advantageous for high-throughput drug development. Perspectives for pharmaceutical screening at XFEL sources using the example of Lassa virus endonuclease.,Falke S, Reinke PYA, Rosenberg D, Fischer P, Meyer J, Galchenkova M, Tolstikova A, Mariani V, Senst JM, Lewe P, Witt S, Wagner A, Chapman HN, Hunter M, Gunther S, Meents A Acta Crystallogr D Struct Biol. 2026 Oct 1;82(Pt 10):1181-1194. doi: , 10.1107/S2059798326009435. Epub 2026 Sep 25. PMID:42789322[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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